package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import static com.hmdp.utils.RedisConstants.LOCK_ORDER;
import static com.hmdp.utils.RedisConstants.SECKILL_STOCK_KEY;
import static com.hmdp.utils.SystemConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;

    //加载lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 *1024);
    private class VoucherOrderHandler implements Runnable{
        String queneName = "stream.orders";
        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取消息队列中的订单信息XREADgroup GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS stream.order >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queneName, ReadOffset.lastConsumed())
                    );

                    //2.判断消息是否获取成功
                    if (list == null || list.isEmpty()){
                        //2.1如果获取失败，说明没有消息，继续下一次循环
                        continue;
                    }
                    //3.解析消息中的订单消息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    //3.1如果获取成功，可以下单，创建订单
                    handleVoucherOrder(voucherOrder);

                    //4.ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(queneName,"g1",record.getId());
                } catch (Exception e) {
                    log.error(ORDER_UNUSUAL,e);
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true){
                try {
                    //1.获取pending-list中的订单信息XREADgroup GROUP g1 c1 COUNT 1 STREAMS stream.order 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queneName, ReadOffset.from("0"))
                    );

                    //2.判断消息是否获取成功
                    if (list == null || list.isEmpty()){
                        //2.1如果获取失败，说明pending-list没有消息，继续下一次循环
                        break;
                    }
                    //3.解析消息中的订单消息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    //3.1如果获取成功，可以下单，创建订单
                    handleVoucherOrder(voucherOrder);

                    //4.ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(queneName,"g1",record.getId());
                } catch (Exception e) {
                    log.error(ORDER_UNUSUAL,e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }
    }

//    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 *1024);
//    private class VoucherOrderHandler implements Runnable{
//        @Override
//        public void run() {
//            while (true) {
//                try {
//                    //1.获取列表中的订单信息
//                    VoucherOrder voucherOrder = orderTasks.take();
//                    //2.创建订单
//                    handleVoucherOrder(voucherOrder);
//                } catch (InterruptedException e) {
//                    log.error(ORDER_UNUSUAL,e);
//                }
//            }
//        }
//    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1.获取用户
        Long userId = voucherOrder.getUserId();
        //2.创建锁对象
        RLock lock = redissonClient.getLock(LOCK_ORDER + userId);
        //3.获取锁
        boolean tryLock = lock.tryLock();
        //4.判断锁是否获取成功
        if (!tryLock) {
            //获取锁失败，返回错误或重试
             log.error(ONE_TO_ONE_ORDER);
             return;
        }
        try {
            proxy.createVoucherOrder(voucherOrder);
        }finally {
            lock.unlock();
        }
    }

    private IVoucherOrderService proxy;
    @Override
    public Result seckillVoucher(Long voucherId){
        //获取用户
        Long userId = UserHolder.getUser().getId();
        //获取订单id
        long orderId = redisIdWorker.nextId("order");
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString(),
                String.valueOf(orderId)
        );
        //2.判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            //2.1不为0，代表没有购买资格
            return Result.fail(r == 1 ? STOCK_NOT_ENCOUGH : ONE_TO_ONE_ORDER);
        }
        //3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        //4.返回订单id
        return Result.ok(orderId);
    }

//    @Override
//    public Result seckillVoucher(Long voucherId) {
//        //获取用户
//        Long userId = UserHolder.getUser().getId();
//
//        //1.执行lua脚本
//        Long result = stringRedisTemplate.execute(
//                SECKILL_SCRIPT,
//                Collections.emptyList(),
//                voucherId.toString(),
//                userId.toString()
//        );
//        //2.判断结果是否为0
//        int r = result.intValue();
//        if (r != 0) {
//            //2.1不为0，代表没有购买资格
//            return Result.fail(r == 1 ? STOCK_NOT_ENCOUGH : ONE_TO_ONE_ORDER);
//        }
//        //2.2为0，代表有购买资格，把下单信息保存到阻塞队列
//        //2.3.创建订单
//        VoucherOrder voucherOrder = new VoucherOrder();
//        //2.3.1设置订单id
//        long orderId = redisIdWorker.nextId("order");
//        voucherOrder.setId(orderId);
//        //2.3.2设置用户id
//        voucherOrder.setUserId(userId);
//        //2.3.3设置代金券id
//        voucherOrder.setVoucherId(voucherId);
//        //2.4放入阻塞队列
//        orderTasks.add(voucherOrder);
//
//        //3.获取代理对象
//        proxy = (IVoucherOrderService) AopContext.currentProxy();
//        //4.返回订单id
//        return Result.ok(orderId);
//    }

//    @Override
//    public Result seckillVoucher(Long voucherId) {
//        //1.查询优惠券
//        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
//        //2.判断秒杀是否开始
//        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
//            //秒杀尚未开始
//            return Result.fail(SECKILL_NOT_START);
//        }
//        //3.判断秒杀是否已经结束
//        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
//            //秒杀已经结束
//            return Result.fail(SECKILL_HAVE_END);
//        }
//        //4.判断库存是否充足
//        if (voucher.getStock() < 1) {
//            //5.库存不充足
//            return Result.fail(STOCK_NOT_ENOUGH);
//        }
//
//        return createVoucherOrder(voucherId);
//        Long userId = UserHolder.getUser().getId();
//        //创建锁对象
//        //SimpleRedisLock lock = new SimpleRedisLock(stringRedisTemplate, "order" + userId);
//        //通过redisson获取锁
//        RLock lock = redissonClient.getLock(LOCK_ORDER + userId);
//        //获取锁
//        boolean tryLock = lock.tryLock();
//
//        //判断是否获取锁成功
//        if (!tryLock) {
//            //获取锁失败，返回错误或重试
//            return Result.fail(ONE_TO_ONE_ORDER);
//        }
//
//        //根据用户id去生成锁，并对整个方法进行锁，实现一人一锁
        //synchronized (userId.toString().intern()) {
//        try {
//            //拿到当前对象的IVoucherOrderService代理对象，防止事务失效
//            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
//            return  proxy.createVoucherOrder(voucherId);
//        } finally {
//            //释放锁
//            lock.unlock();
//        }
//    }
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //6.实现一人一单
        //获取用户id
//        Long userId = UserHolder.getUser().getId();
        //因为现在是在子线程里，所以不能通过UserHolder直接获取userId
        Long userId = voucherOrder.getUserId();


        // 由于在handleVoucherOrder中已经获取了锁
        //创建锁对象
//        RLock lock = redissonClient.getLock(LOCK_ORDER + userId);
//        //尝试获取锁
//        boolean tryLock = lock.tryLock();
//        //判断是否获取锁成功
//        if (!tryLock) {
//            //获取锁失败
//            return Result.fail();
//        }

        //6.1查询订单
        Long count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        //6.2查询是否存在，判断该用户是否已经买过
        int r = count.intValue();
        if (r > 0) {
            //用户已经买过了
            log.error(ONE_TO_ONE_ORDER);
            return;
        }
        //7.如果库存充足，扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")    //set stock = stock - 1
                /*添加了一个乐观锁，在更新数据之前判断数据是否被其他线程修改过.eq("stock",voucher.getStock())
                    券还未卖完，就会产生线程安全问题，使券无法全部售卖
                   */
                /*
                  改进：将.eq("stock",voucher.getStock())改为.gt("stock",0),
                  线程安全问题得到好的解决，并且优惠券可以完全售卖。
                    */
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock", 0) //where id = ? and stock = ?
                .update();
        if (!success) {
            //扣减失败
            log.error(STOCK_NOT_ENCOUGH);
            return;
        }
        //由于在handleVoucherOrder中已经创建了
//            //8.创建订单
//            VoucherOrder voucherOrder = new VoucherOrder();
//            //8.1设置订单id
//            long orderId = redisIdWorker.nextId("order");
//            voucherOrder.setId(orderId);
//            //8.2设置用户id
//            voucherOrder.setUserId(userId);
//            //8.3设置代金券id
//            voucherOrder.setVoucherId(voucherOrder);
        //8.4将订单写入数据库
        save(voucherOrder);
        //9.返回订单id
    }
}
